Definitely a motor, two coils so can series or parallel connect them, depends if you have a valve, high impedance, or transistor, low impedance, servo amplifier.

Sure I have a copy of the Muirhead book, somewhere. I had hundreds of synchros etc and used to sell them, but all of a sudden no one wanted them so scrapped. I would point out that the brushes a re what is known as precious metal, a gold alloy, about £600 per oz.

Just scrapped the test angle unit, might have a 400Hz supply if wanted.